The option cursor-file takes a filename as argument. If the file exists and
contains a valid cursor, this is used to start the output after this position.
At the end, the last cursor gets written to the file.
This allows for an easy implementation of a timer that regularly looks in the
journal for some messages.
journalctl --cursor-file err-cursor -b -p err
journalctl --cursor-file audit-cursor -t audit --grep DENIED
Or you might want to walk the journal in steps of 10 messages:
journalctl --cursor-file ./curs -n10 --since=today -t systemd
Also, while we are at it, beef it up, by adding json-seq support (i.e.
https://tools.ietf.org/html/rfc7464). This is particularly useful in
conjunction with jq's --seq switch.
When dealing with a large number of template instances, for example
when launching daemons per VRF, it is hard for operators to correlate
log lines to arguments.
Add a new with-unit mode which, if available, prefixes unit and user
unit names when displaying its log messages instead of the syslog
identifier. It will also use the full timestamp with timezones, like
the short-full mode.
This new output mode formats all timestamps using the usual format_timestamp()
call we use pretty much everywhere else. Timestamps formatted this way are some
ways more useful than traditional syslog timestamps as they include weekday,
month and timezone information, while not being much longer. They are also not
locale-dependent. The primary advantage however is that they may be passed
directly to journalctl's --since= and --until= switches as soon as #3869 is
merged.
While we are at it, let's also add "short-unix" to shell completion.
